Monitoring Aflatoxin M1 in Milk From Selected Iranian Provinces Using Different Assays: Seasonal Trends and Processing Effects

Accurate and rapid determination of aflatoxin M1 (AFM1) is essential for ensuring the safety of milk and dairy products. This study is the first to integrate seasonal analysis, processing effects, multi-method comparison, and MOE-based risk assessment of AFM1 in Iranian milk, providing comprehensive insights for food safety monitoring. A total of 227 raw milk samples from 12 provinces were analyzed across different seasons using immunochromatography, ELISA, and HPLC. The prevalence of AFM1 exceeding the legal limit of 0.10 μg/kg, as set by the Institute of Standards and Industrial Research of Iran (ISIRI), was 9.7% in spring, 13.3% in summer, 3.7% in autumn, and 26.4% in winter. The highest average AFM1 concentrations were recorded in winter and summer, while the lowest occurred in spring and autumn. The study also evaluated the effects of pasteurization and spray-drying on AFM1 levels in skim milk and skim milk powder, with HPLC analysis showing no significant changes (<i>p</i> ≥ 0.05) post-processing. Risk assessment calculated the estimated daily intake (EDI) and hazard index (HI) for liver cancer, with EDI in winter reaching 62.58 ng/kg body weight and HI at 1.06, based on a tolerable daily intake (TDI) of 0.2 ng/kg bw/day derived from TD50 with a safety factor of 50,000. These results highlight the need for continuous monitoring and regulation of AFM1 to safeguard public health. Among the methods tested, immunochromatography demonstrated clear advantages over ELISA and HPLC, making it an efficient and practical tool for rapid preliminary detection of AFM1 in milk.